Grizzly G9249 owner manual To confirm that the bearings are correctly pre- loaded

9.Move the carriage toward the spindle an additional 0.100".

10.Tighten the inner spanner nut until you see the motion of the dial indicator needle just barely stop moving. During the spanner nut tightening process, rock the spindle back and forth slightly to make sure the spindle bear- ings seat properly in the races.

Note: When the dial indicator needle stops moving, there will be no spindle end-play and no bearing preload. It is essential that you find this exact point without tightening the inner spanner nut too much and inadvertently preload the spindle bearings.

Since it can take great effort to turn the inner spanner nut, you may find it difficult to know if you have gone past the zero end-play point or not. You may find it easier to have an assistant watch the dial for you while you tighten the spanner nut. If you think you may have gone past the zero end-play point, take the time to unload the bearings as described in earlier steps, then re-tighten the spanner nut until you know you have reached the cor- rect setting.

11.To set the correct amount of spindle bear- ing preload, rotate the inner spindle lock nut clockwise an additional 0.13" along its cir- cumference. See Figure 105 for an example of this measurement.

0.13" Travel

Figure 105. Example of final inner spanner nut

travel.

12.Without causing the inner spanner nut to tighten any further, install and tighten the outer spanner nut against the inner nut.

Note: Do not overtighten the outer spanner nut because additional preload can force the bearings even tighter against the races in the headstock and cause the headstock to com- press or crack, or cause bearing failure.

13.Re-install the change gear door.

To confirm that the bearings are correctly pre- loaded:

1.Make sure all safety precautions have been taken and setup steps are complete to make the lathe fully operational.

2.Remove all tools and materials used during the bearing preload process.

3.Set the spindle speed to its highest setting.

4.Connect the lathe to power and turn it ON.

5.Let the lathe run for 20 minutes.

6.Turn the spindle OFF, disconnect the lathe from power, and check the temperature of the spindle.

—If the inboard end of the spindle tube is slightly warm to the touch, you have the correct bearing preload.

—If the inboard end of the spindle tube is hotter than you can comfortably keep your hand on, the preload is too tight and you must repeat the spindle bearing preload adjustment procedure.

-60- G9249  12" x 37" Belt Drive Gap Bed Lathe